DNS Extensions for IPv6

A new resource record that is defined as an AAAA record has been specified
by RFC 1886. This AAAA record maps a host name into an 128–bit IPv6
address. The PTR record is still used with IPv6 to map IP addresses into host
names. The thirty two 4–bit nibbles of the 128–bit address are
reversed for an IPv6 address. Each nibble is converted to its corresponding
hexadecimal ASCII value. Then ip6.int is appended.